KR100338334B1 - Shadow mask assembly and color cathode-ray tube with the same - Google Patents

Abstract

A shadow mask assembly is provided that reduces the required tension applied to the shadow mask, and the weight and cost of the assembly itself. This assembly comprises: (a) a pair of bars arranged substantially parallel at a specific distance, the metal having a first coefficient of thermal expansion; (b) a pair of arms fixed to the pair of bars in such a manner that each of the pair of arms is coupled together with the pair of bars, the pair of arms having the force to move the pair of bars spaced apart from each other. Add, and comprise a frame having a second coefficient of thermal expansion, the frame having a substantially rectangular opening with the pair of bars; And (c) a shadow mask fixed to the pair of bars to cover the opening of the frame, the shadow mask having the pair of arms by moving the pair of bars spaced apart from each other by the force of the pair of arms. By applying tension in a direction substantially perpendicular to the bar of the mask, the mask maintains its particular shape, and the mask is made of a metal having a third coefficient of thermal expansion low enough to suppress the doming phenomenon, The third coefficient of thermal expansion of the mask is lower than the second coefficient of thermal expansion of the pair of arms.

Description

SHADOW MASK ASSEMBLY AND COLOR CATHODE-RAY TUBE WITH THE SAME}

The present invention relates to a shadow mask assembly and a color cathode ray tube (CRT) having the same, in particular, a shadow mask assembly having a structure for maintaining a mask in a specific form by applying a tension to a shadow mask to a frame, and the assembly It is related with the equipped color CRT.

Shadow mask type color CRTs are widely used. In this type of color CRT, the shape of the shadow mask is usually formed to form part of the spherical surface. Since the shadow mask is fixed in the vicinity of the screen made of glass, the screen form also needs to be formed in a spherical surface.

Recently, there has been a trend to form the screen form as part of a cylindrical surface or a plane. This is because the visibility of the color CRT can be improved. In this case, needless to say, it is necessary to form the screen form as part of the cylindrical surface or the plane according to the mask form.

However, as is known, the shadow mask is formed of a very thin, rectangular metal plate and has very low mechanical rigidity because it has small, many openings for uniformly arranged color selection. As a result, the mask cannot maintain the cylindrical or planar shape without applying any external force. Thus, when the mask is secured to the frame, by applying a suitable tension in one or two directions to the flat mask once or twice, the mask is applied in the desired cylindrical or planar form by applying the appropriate tension in the desired direction. Keep it.

Japanese Unexamined Patent Publication No. 8-77936, published in March 1996, which will be described below with reference to FIG. 1, discloses an example of a structure in which a tension is applied to a shadow mask to fix the mask to a frame.

As shown in FIG. 1, the prior art shadow mask assembly 200 consists of a pair of curved bars 201a and 201b, a pair of arms 202a and 202b, and a rectangular shadow mask 203. . The pair of bars 201a and 201b are fixed to the pair of arms 202a and 202b to constitute a frame that supports the mask 203.

Each bar 201a and 201b has an L-shaped cross section and is curved to form part of a cylindrical surface. Each arm 202a and 202b is bent to have a U shape. The mask 203 curved to form part of the cylindrical surface is a small, many opening 204 for uniformly arranged color selection that allows three electron beams of red (R), green (G) and blue (B) to pass through. Has

Both ends of the mask 203 are fixed to the curved upper surfaces of the bars 201a and 201b by welding, respectively. Thus, the mask 203 covers or closes the rectangular openings formed by the bars 201a and 201b and the arms 202a and 202b (ie, formed by the frame). In this state, the arms 202a and 202b have the elasticity to move the bars 201a and 201b outwards, respectively. By this elasticity, the fixed ends of the mask 203 are pulled apart from each other. As a result, an expansion force for moving the fixed ends of the mask 203 so as to be spaced apart from each other is generated in the mask 203, thereby maintaining the shape of the mask 203.

According to 8-77936, the bars 201a and 201b (constituting the frame) and the arms 202a and 202b are made of chromium-based stainless steel, and the shadow mask 203 is made of iron.

9-77936 does not disclose a method for assembling the mask assembly 200 of the prior art. However, the assembly 200 is expected to be assembled in the following manner.

First, both ends of the arm 202a are fixed to specific positions of the bars 201a and 201b by welding, respectively. Similarly, both ends of the arm 202b are fixed to specific positions of the bars 201a and 201b by welding, respectively. Thus, the bars 201a and 201b are spaced apart in parallel at a certain distance from each other to form a frame having a substantially rectangular shape.

Next, by applying an external force to the bars 201a and 201b, the two ends of the arms 202a and 202b are bent slightly inward. Next, with both ends of the arms 202a and 202b bent inward, both ends of the mask 203 are fixed to the curved upper surfaces of the bars 201a and 201b by welding, respectively. Thereafter, the application of external forces or forces is stopped to bring both ends of arms 202a and 202b back to their original positions. Thus, outer elasticity is generated to move the bars 201a and 201b to be spaced apart from each other, so that a specific tension is applied to the mask 203 in a direction perpendicular to the bars 201a and 201b. With this particular tension, the desired shape of the mask 203 can be kept unchanged even though the mechanical strength is very low.

In general, when the color CRT is in operation, most of the R, G, and B electron beams collide with the mask 203 so that the temperature of the mask 203 rises to nearly 100 ° C. This rise in temperature causes the mask 203 to partially thermally expand, causing the opening 204 to move to a desired location. In this state, the R, G, and B electron beams may arrive incorrectly on the fluorescent surface disposed between the mask 203 and the screen, and the color purity may be inferior. This phenomenon is called "doming".

The tension applied to the shadow mask 203 not only maintains the shape of the mask but also prevents the doming phenomenon. Therefore, if the mask 203 has a large coefficient of thermal expansion, the tension must be increased in accordance with the coefficient value.

In the shadow mask assembly 200 of the prior art shown in Fig. 1, the shadow mask 203 is made of iron, so that the thermal expansion coefficient of the mask 203 is about 120 x 10 ^-7 / ° C at room temperature. Thus, in order to absorb thermal expansion of the mask 203 and mechanically maintain the desired shape of the mask 203, a tension as high as about 500 to 1000 kg is required. As a result, the bars 201a and 201b and the arms 202a and 202b must be stronger in accordance with the amount of tension applied, thus increasing the weight and manufacturing cost of the assembly 200.

In addition, in the welding process of the mask 203, a large pressure needs to be applied to the arms 202a and 202b, and for this purpose, a large and expensive facility is required. This further increases the manufacturing cost of the assembly 200.

It is therefore an object of the present invention to provide a shadow mask assembly that reduces the required tension applied to the shadow mask, and a color CRT with the assembly.

Another object of the present invention is to provide a shadow mask assembly which reduces the weight and manufacturing cost of the shadow mask assembly, and a color CRT having the assembly.

It is yet another object of the present invention to provide a shadow mask assembly that does not require large, expensive equipment to tension the shadow mask, and a color CRT with the assembly.

The above and other objects not specifically mentioned will become apparent to the person skilled in the art from the following description.

According to a first aspect of the present invention, there is provided a device comprising: (a) a pair of bars arranged substantially parallel to a certain distance and having a first coefficient of thermal expansion;

(b) a pair of arms fixed to the pair of bars in such a manner that each of the pair of arms is coupled together with the pair of bars, the pair of arms having the force to move the pair of bars spaced apart from each other. Add, and comprise a frame having a second coefficient of thermal expansion, the frame having a substantially rectangular opening with the pair of bars; And

(c) a shadow mask fixed to the pair of bars to cover the opening of the frame, the shadow mask having the pair of arms by the force of the pair of arms moving the pair of bars spaced apart from each other; By applying tension in a direction substantially perpendicular to the bar, the mask is made of a metal having a third coefficient of thermal expansion low enough to maintain its particular shape and suppress the doming phenomenon, And a third coefficient of thermal expansion is lower than the second coefficient of thermal expansion of the pair of arms.

According to the shadow mask assembly according to the first aspect of the present invention, the shadow mask is made of a metal having a third coefficient of thermal expansion low enough to suppress the doming phenomenon, so that additional tension is applied to the mask to suppress the doming phenomenon. It is not added. This means that the tension for holding the mask in that particular form is reduced, in other words, the required tension applied to the mask is reduced.

As a result, the required mechanical strength for the pair of bars and the pair of arms is lowered, so that the weight and manufacturing cost of the bar pairs can be reduced (therefore, the weight and manufacturing cost of the shadow mask assembly itself can be reduced. have). At the same time, in the welding process, the required force applied to the pair of arms can be lowered, thereby eliminating the need for large and expensive equipment to apply tension to the shadow mask.

In a preferred embodiment of the shadow mask assembly according to the first aspect of the present invention, the first coefficient of thermal expansion of the pair of bars is higher than the second coefficient of thermal expansion of the pair of arms. In this embodiment, there is another advantage that the disadvantage due to the thermal expansion difference between the pair of bars and the mask is less likely to occur.

In another preferred embodiment of the shadow mask assembly according to the first aspect of the invention, the first coefficient of thermal expansion of the pair of bars is approximately equal to the third coefficient of thermal expansion of the shadow mask. In this embodiment, in the manufacturing process of the color CRT, the shadow mask assembly may be subjected to plastic deformation and / or wrinkling of the mask even in a thermal history of the highest temperature of about 500 ° C. and in a high temperature operating environment of about 100 ° C. There is an additional advantage that no disadvantages arise. This is because the thermal expansion difference hardly occurs between the pair of bars and the mask.

In another preferred embodiment of the shadow mask assembly according to the first aspect of the invention, the metal of the pair of bars and the shadow mask consists of an invariant steel (ie, an iron alloy containing 36% nickel) and a pair of The metal of the arm is at least one selected from the group consisting of iron, chromium-iron alloys, and chromium-iron-molybdenum alloys.

According to a second aspect of the invention, there is provided a color CRT composed of a shadow mask assembly according to the first aspect of the invention.

By using the color CRT according to the second aspect of the present invention, the shadow mask assembly according to the first aspect of the present invention is included, so that a light, inexpensive and high quality color CRT can be realized.

1 is a schematic perspective view showing the construction of a shadow mask assembly for a color CRT of the prior art;

Figure 2 is a schematic perspective view showing the configuration of a shadow mask assembly for a color CRT according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: shadow mask assembly

101a and 101b: a pair of curved bars

102a and 102b: pair of arms

103: mask

104: opening

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present invention will be described in detail.

As shown in FIG. 2, the shadow mask assembly 100 according to an exemplary embodiment of the present invention includes a pair of curved bars 101a and 101b disposed parallel to each other at a specific distance, and the bars 101a and 101b. And a pair of arms 102a and 102b fixed to and spaced from each other, and a rectangular shadow mask 103 fixed to the bars 101a and 101b.

The pair of arms 102a and 102b are secured to the pair of bars 101a and 101b in such a manner that each of the arms 102a and 102b is connected together with the bars 101a and 101b, thereby providing a mask 103. Configure the frame to support it.

Each of the bars 101a and 101b has an L-shaped cross section and is curved to form part of a cylindrical surface. Each of the arms 102a and 102b is bent to have a U-shaped shape. The mask 103 curved to form part of the cylindrical surface has a constant number of small, large openings 104 for color selection that allow the electron beams of R, G and B to pass through the mask 103.

Both ends of the mask 103 are fixed to the curved upper surfaces of the bars 101a and 101b by welding, respectively. Thus, the mask 103 covers or closes the rectangular openings formed by the bars 101a and 101b and the arms 102a and 102b (ie, formed by the frame). In this state, the arms 102a and 102b have the elasticity to move the bars 101a and 101b outwards, respectively. By this elasticity, the fixed ends of the mask 103 are pulled apart from each other. As a result, a tension is generated in the mask 103 to move the fixed ends of the mask 103 so as to be spaced apart from each other, so that the curved shape of the mask 103 is maintained.

Bars 101a and 101b and shadow mask 103 are invariant alloys (ie, iron containing 30% nickel) with a coefficient of thermal expansion as low as about 10 × 10 ⁻⁷ / ° C., sufficient to suppress doming phenomenon. Alloy).

Since the manufacturing method of the shadow mask assembly 100 is the same as described in the assembly 200 of the prior art, a description thereof will be omitted.

In the shadow mask assembly 100 according to the exemplary embodiment of the present invention, the shadow mask 103 is formed of an invariant cavity, and thus the thermal expansion coefficient of the mask 203 of the mask 103 is iron (ie, 120 × 10). It is low enough to suppress the doming phenomenon by about one tenth (1/10) of -7 / degreeC). Therefore, in order to suppress the doming phenomenon, the tension is hardly additionally applied to the mask 103. This means that the tension for maintaining the mask 103 in its form is reduced, in other words, the required tension applied to the mask 103 is reduced.

As a result, the required mechanical strength for the bars 101a and 101b and the arms 102a and 102b can be reduced, whereby the bars 101a and 101b and the arms 102a and 102b (ie, the shadow mask assembly itself) Can reduce the weight and manufacturing cost. At the same time, the required tension applied to the arms 102a and 102b in the welding process can be reduced, thereby eliminating the need for a large-scale and expensive facility for tensioning the shadow mask 103.

Needless to say, any other metal having a preferably low coefficient of thermal expansion may be used for the metal of the mask 103. In this case, the tension can be reduced according to the count value.

In this embodiment, the invariant steel is used for the pair of bars 101a and 101b and the mask 103. Therefore, in the color CRT manufacturing process, the disadvantages such as plastic deformation and / or wrinkling of the mask do not occur even in the thermal history of the highest temperature of the shadow mask assembly of about 500 ° C. and in the high temperature operating environment of about 100 ° C. There is an additional advantage. This is because the thermal expansion difference hardly occurs between the pair of bars 101a and 101b and the mask 103.

In the present invention, any other metal having a preferably low coefficient of thermal expansion may be used for the bars 101a and 101b. However, because of the additional advantages described above, it is preferable to use a constant steel for the bars 101a and 101b.

Alternatively, since the bars 101a and 101b are not in contact with the mask 103, it is not necessary to use any metal having a preferably low coefficient of thermal expansion, such as invariant, for the arms 102a and 102b. Although such a metal can be used for the arms 102a and 102b, it is not preferable because of the high price. In view of price, it is desirable to select and use any metal that produces the desired elasticity for the arms 102a and 102b. For example, it is preferable to use iron (Fe), chromium-iron (Cr-Fe) alloys, and / or chromium-iron-molybdenum (Cr-Fe-Mo) alloys as metals for the arms 102a and 102b. Do.

In the above-described embodiment, the mask 103 is curved to form part of the cylindrical surface. However, the mask 103 can be curved to form part of the plane. In this case, any other assembly structure is the same as described above except that the pair of bars 101a and 101b change linearly. Therefore, description thereof is omitted for simplicity.

While the preferred form of the invention has been described, it will be understood that modifications may be made by those skilled in the art without departing from the spirit of the invention. Accordingly, the scope of the invention is to be determined only by the following claims.

According to the present invention, the shadow mask is made of a metal having a third coefficient of thermal expansion low enough to suppress the domming phenomenon, so that no additional tension is applied to the mask to suppress the domming phenomenon. Thus, the tension for holding the mask in that particular form is reduced.

As a result, the required mechanical strength for the pair of bars and the pair of arms is lowered so that the weight and manufacturing cost of the bar and arm pairs can be reduced. In other words, the weight and manufacturing cost of the shadow mask assembly itself can be reduced. At the same time, in the welding process, the required force applied to the pair of arms can be lowered, thereby eliminating the need for large and expensive equipment to apply tension to the shadow mask.

Claims (6)

In the shadow mask assembly, (a) a pair of bars disposed substantially parallel to a certain distance and composed of a metal having a first coefficient of thermal expansion; (b) a pair of arms fixed to the pair of bars in such a manner that each of the pair of arms is coupled together with the pair of bars, the pair of arms having the force to move the pair of bars spaced apart from each other. Add, and comprise a frame having a second coefficient of thermal expansion, the frame having a substantially rectangular opening with the pair of bars; And (c) a shadow mask fixed to the pair of bars to cover the opening of the frame, the shadow mask having the pair of arms by the force of the pair of arms moving the pair of bars spaced apart from each other; By applying tension in a direction substantially perpendicular to the bar, the mask is made of a metal having a third coefficient of thermal expansion low enough to maintain its particular shape and suppress the doming phenomenon, The third coefficient of thermal expansion is lower than the second coefficient of thermal expansion of the pair of arms − Shadow mask assembly comprising a. The shadow mask assembly of claim 1, wherein the first coefficient of thermal expansion of the pair of bars is higher than the second coefficient of thermal expansion of the pair of arms. The shadow mask assembly of claim 1, wherein the first coefficient of thermal expansion of the pair of bars is approximately equal to the third coefficient of thermal expansion of the shadow mask. The method of claim 1, wherein the metals of the pair of bars and the shadow mask are invariant steel and the metal of the pair of arms is at least selected from the group consisting of iron, chromium-iron alloys, and chromium-iron molybdenum alloys. Shadow mask assembly, characterized in that one. The shadow mask assembly of claim 1, wherein each of the pair of bars is curved to form part of a cylindrical surface. A color CRT comprising a shadow mask assembly according to any one of claims 1 to 5.